How to clear Textbox if case not found? - excel

Question

I scan a barcode into an ActiveX textbox. It selects the relevant case and performs the calculation/event depending on the barcode. Every code is connected to an event.
One out of 100+ scans is not correctly decoded to the computer. As such, it does not match a case and does not make the textbox value "". It then appends to every other scan entering into the textbox. Aka "15 - FT - R" might scan in as "15 - FT -R".
I need the code to recognize this as a non case and delete it.
Since the barcode scans each character one at a time, nothing is equal to a case until the barcode value has completely entered the textbox.
Is there any way to tell if the barcode info is done being scanned?
My biggest challenge is how to stop the rest of the text from entering the box once it does not match a case.
My next biggest challenge is setting variables.
Private Sub TextBox1_Change()
Dim ws As Worksheet, v, e, f, g, k, i4
Set ws = Worksheets("Sheet1")
v = TextBox1.Value
e = 0
f = 0
g = 0
k = 0
i4 = 0
Select Case v
Case "15 - FT - R": f = 5
e = 11
k = 2
g = "15 - FT - R"
Case "150 - FT - C": f = 30
e = 11
k = 2
g = "150 - FT - C"
Case "R Waste": f = 4
e = 9
k = 2
g = "R Waste"
Case "C Waste": f = 4
e = 10
k = 2
g = "C Waste"
Case "Accident - 4": k = 5
'other cases here....
End Select
'e = Sets the column reference for taking 1 master roll out
'f = Sets the row reference for taking 1 master roll out
'g = name of the item being used for the time stamp
'k = Case Selection
'i4 = Count for Cutting Station 1 timestamp, row reference
If k = 2 Then
'Coating Station
'accidental scan references for coating
ws.Cells(4, 4) = f
ws.Cells(5, 4) = e
ws.Cells(f, e) = ws.Cells(f, e) + 1
'adds master roll
i4 = ws.Cells(4, 30)
'count function
Cells(i4, 25).Value = Format(Now, "mm/dd/yyyy AM/PM h:mm:ss")
Cells(i4, 26).Value = g
'formatting timestamp
TextBox1.Activate
TextBox1.Value = ""
'e = Sets the column reference for taking 1 master roll out
'f = Sets the row reference for taking 1 master roll out
'k = Case Selection
'i4 = Count for Cutting Station 1 timestamp, row reference
ElseIf k = 5 Then
'Accidental scan
f = ws.Cells(4, 4)
e = ws.Cells(5, 4)
ws.Cells(f, e) = ws.Cells(f, e) - 1
i4 = ws.Cells(4, 30)
'count function
Cells(i4, 25).Value = Format(Now, "mm/dd/yyyy AM/PM h:mm:ss")
Cells(i4, 26).Value = "Accident"
'formatting timestamp
TextBox1.Activate
TextBox1.Value = ""
End If
End Sub

Answer 1

Set TextBox properties:
EnterKeyBehavior TRUE
Multiline TRUE
Use this in your VBA _Change call back:
If Not Right(Me.Scan.Value, 1) = vbLf Then Exit Sub
In essence, we're now just looking for the LF character after enabling the multiline capability of the textbox.